In typical installations, low voltage pendant lamps such as LED lamps of 5 watt or less and halogen lamps of 50 watt or less, are suspended at selected heights from their coaxial power cords which comprise a negative inner conductor within insulation surrounded by a positive (earth) outer conductor of metal braid.
For esthetic reasons, it is frequently necessary to effect relatively small readjustments to the heights of individual lamps after installation, especially, for example, when installing a row of pendant lamps at identical heights. Previously, to effect the readjustments, it has typically been necessary to release a screw which clamps the power cord to the canopy, release/lower the canopy cover, manually pull more cord into the canopy to raise the lamp or release cord from the canopy by pushing/pulling through the canopy cover to lower the lamp and, then to raise/reseat the canopy cover and re-tighten the cord clamping screw.
Although, any excess cord is readily accommodated in concealed condition within in the canopy, as a result of the outer metal braid being spirally woven around the insulation, any manual pulling or pushing force exerted on the outside of the cord tends to shift the metal braid along the cord insulation relative to the inner conductor, with the risk that the braid may be shifted into electrical contact with the stripped/exposed terminated end of inner conductor or with conducting portions of an associated connector (such a wire nut) used to connect the inner conductor to a (negative) live/power wire from the transformer, resulting in a short circuit.
To eliminate such risk, it is normally considered prudent to lower/unseat the canopy cover from the fixture to provide visual and manual access to the terminated end of the cord in the canopy, to enable the terminated cord to be checked and re-adjust/re-trim the braid to obviate any risk of a short circuit.
Clearly, such re-termination or braid adjustment steps are undesirably time consuming and to be avoided, if possible. Furthermore, as the clamping screw must clamp the cord sufficiently tightly to carry the weight of the lamp, there can be an increased risk of the technician overtightening the clamping screw, penetrating the insulation and short circuiting the ground braid to the inner conductor.